1. Field of the Invention
The present invention relates to a conductor supporting apparatus for gas insulated equipment and, more particularly, to a conductor supporting apparatus for gas insulated equipment provided with an insulating spacer having a high dielectric strength in which the deterioration of insulation performance is small even when conductive foreign matters such as metal are deposited.
2. Description of the Prior Art
For the insulating spacer which is used in the grounded tank of gas insulated equipment and supports the conductor, the shape of the insulating spacer which can cope with the cases where conductive foreign matters such as metal are deposited on the surface of such an insulating spacer and the like is disclosed in Cigre Report 15-07, 1978 Session, August 30 to September 7, "LONG DURATION TESTS ON EPOXY INSULATORS IN SF.sub.6 GAS". A feature of such an insulating spacer is that a plurality of creepage flanges are formed on the creeping surface. Some consideration has been given with respect to which shapes of creepage flanges are effective under the situations where conductive foreign matters such as metal enter the gas insulated equipment and are deposited onto the surface of the insulating spacer. In addition, there also has been considered an approach whereby the creepage flanges are not directly formed on the insulating spacer itself but barrier-like insulating members are provided near the surface of the insulating spacer (for example, refer to Japanese Utility Model Laid-Open No. 107168/78). However, when considering the easiness of manufacturing and the costs and the like, it is desirable to reduce the number of barriers as much as possible and to reduce the changes from the conventional structure as much as possible. In particular, these considerations become more and more significant subjects in gas insulated equipment in which high voltage and miniaturization are intended to be attained.
A conventional use example of the insulating spacer in a gas insulated bus-bar, which is the gas insulated equipment selected for the purpose of illustration, will now be described in more detail. In a gas insulated bus-bar, a high voltage conductor for current supply is arranged in a cylindrical grounded tank, and the high voltage conductor is insulated and supported from the grounded tank by an insulating spacer. Insulating gases such as SF.sub.6 and the like which have excellent insulation performance are filled in the grounded tank of a gas insulated bus-bar or other such gas insulated equipment. If conductive foreign matters such as metal pieces should enter the gas insulated equipment, these metal pieces are subjected to electrostatic forces by the electric field in the gas insulated equipment, so that they float. In other words, they float in the equipment although they depend on the sizes of conductive foreign matters or the electric field strengths. In the worst case, the conductive foreign matters are deposited onto the surface of the insulating spacer or approach the high voltage conductor, so that an unexpected accident may occur. Therefore, it is an important subject in the improvement of the reliability to obtain an insulating spacer in which the deterioration of the insulation performance is small even under such a situation. As described above, it is effective as a countermeasure for such a problem to form creepage flanges on the insulating spacer. However, since the electric fields are concentrated among the creepage flanges, this method is disadvantageous for the performance when the insulating spacer is cleaned, and at the same time there are the problems such that the conditions in manufacturing and assembling are fairly restricted, and the like.